We propose to develop and test an instrument that will make physical measurements of the optical transfer function (OTF) of the human eye. This instrument, the "Optical Media Analyzer" (OMA) will provide clinicians with numbers that reflect the optical quality of the eye. The OMA is expected to be useful in pre- and post-operative evaluation of cataract, secondary cataract and corneal surgery (including refractive surgery. The OMA is also expected to be useful in following the natural course of cataract development and the natural courses of corneal diseases. It is also expected that the OMA will be an important measure of the optical quality of contact lenses on the eye. Past studies of optical quality of the eye have employed double-pass measures of the line-spread or point-spread function. Such measures include confounding information from backscatter, specular reflections and scattered light in the retina. The proposed design of the OMA will provide for rapid physical measurement of the OTF o the eye, minimizing the contribution of backscattter and specular reflection and factoring out retinal light scatter.